1. Field of the Invention
This invention relates to electroluminescent copolymers with multi-functional monomers. The invention further relates to electronic devices in which an active layer includes such polymeric materials.
2. Description of the Related Art
Electroluminescent (EL) devices (such as light-emitting diodes) are present in many different kinds of electronic equipment. In all such devices, an electroluminescent layer is sandwiched between two electrical contact layers. At least one of the electrical contact layers is light-transmitting so that light can pass through the electrical contact layer. The electroluminescent layer emits light through the light-transmitting electrical contact layer upon application of electricity across the electrical contact layers.
Several classes of photoluminescent polymers have been used as electroluminescent layers, including poly(1,4-phenylene vinylene) and derivatives; polythiophenes, especially, poly(3-alkylthiophenes); poly(p-phenylenes), and alkyl and dialkyl derivatives of polyfluorene. Although these materials are suitable for use as electroluminescent layers, there is an increasing demand for EL devices with improved efficiency and increased operational lifetime. Accordingly, there is a concomitant need for materials which can impart improved efficiency to an EL device.